Non-decimal radices/Convert: Difference between revisions
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If we want to assume a default character set, then a general '''toBase''' (Int -> Int -> String) can be also be derived from '''inBaseDigits'''. |
If we want to assume a default character set, then a general '''toBase''' (Int -> Int -> String) can be also be derived from '''inBaseDigits'''. |
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<lang haskell>import |
<lang haskell>import Control.Arrow (first) |
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import Data.Char (intToDigit) |
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import Data.List (unfoldr) |
import Data.List (unfoldr) |
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import Data.Tuple (swap) |
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inBaseDigits :: String -> Int -> String |
inBaseDigits :: String -> Int -> String |
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inBaseDigits ds n = reverse $ unfoldr go n |
inBaseDigits ds n = reverse $ unfoldr go n |
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where |
where |
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base = length ds |
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go x |
go x |
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| 0 < x = |
| 0 < x = Just $ first (ds !!) (swap $ quotRem x (length ds)) |
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let (d, r) = quotRem x base |
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in Just (ds !! r, d) |
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| otherwise = Nothing |
| otherwise = Nothing |
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